The white rot fungus (Phanerochaete chrysosporium) has been proposed for the bioremediation of xenobiotic polluted soils. This fungus mineralizes a variety of toxic compounds in model systems. Degradation of the xenobiotics is related to the production by the fungus of a complex of enzymes termed ligninases which have reducto-oxidase activity for a variety of chemicals. Successful remediation of soil demands that the fungus survives in the polluted soils and produces effective ligninase activity. However the competitiveness of the fungus with the soil microbes at bioremediation sites is unknown. Nor are the effects of the indigenous microbes on the activity of ligninase complex known. The soil microbes may impose positive or negative effects upon the bioremediation system. This proposal addresses the interaction between P. chrysosporium and fluorescent pseudomonads which are common soil inhabitants. We will determine whether: 1) soil pseudomonads are antagonistic towards the fungus; 2) soil pseudomonads alter ligninase production and activity; 3) the fungus has antibacterial activity because of the ligninase activity; and 4) soil bacteria and fungi coadapt to be mutual colonists. These data may enhance our ability to predict the success of P. chrysosporium at different bioremediation sites or to adjust conditions to help assure success.